Re: reverse polarity
Haven't measured the Crossfire but the GM spec is "less than 50 ma" when turned off. Reattae are 17-20 ma for the keep-alives. Back in the day I just used a battery disconnect on cars that sat but all they had for a drain was a kabang clock.
Today everything except the two Golf Cart batteries in my RV and the H6 in the Crossfire are AGM, either Optima or Duracell. Heep came with one.
Ones I do not drive often all have little 50 ma float chargers and all start quickly even if sitting for a month (I start everything and let idle until warm at least once a month).